A solid oxide fuel cell (SOFC) is comprised of a fuel electrode (anode), an air electrode (cathode) and electrolyte. In order to use the SOFC at a low/middle temperature, the electrolyte should have high conductivity at a low temperature. According as a temperature of the SOFC is lowered, ceria-based electrolyte is used instead of 8-YSZ (YSZ Yttria Stabilized Zircornia) in which Y2O3 is doped into ZrO2. It is caused by that the 8-YSZ has high ion conductivity at a high temperature but has low ion conductivity at a low temperature, whereas the ceria-based electrolyte has high ion conductivity even in the low temperature.
Further, in order to minimize a resistance of the electrolyte, the electrolyte should be provided to be as dense and thin as possible. As the ceria-based electrolyte, CGO (Ce0.9Gd0.1O2) and SDC (Sm0.2Ce0.8O2) are widely used. However, due to a property of the ceria-based electrolyte, it is difficult to form the ceria-based electrolyte to be dense and thin on a porous fuel electrode.
In a general method of fabricating the fuel electrode and the electrolyte, the fuel electrode is formed into a pellet, and the electrolyte is formed by a coating or dipping process, thereby fabricating the fuel electrode and the electrolyte. However, since the porous fuel electrode and the ceria-based electrolyte respectively have a different shrinkage, it is difficult to form the thin and dense electrolyte.
In other fabrication method, the fuel electrode and the electrolyte are formed in a sheet shape by a tape casing process and then stacked, thereby fabricating the SOFC. In the case, although it is possible to form the dense electrolyte, there are also some problems that an amount of powder wasted during the fabricating process is very large and a fabricating time is also too long.
Therefore, the present invention provides a new fabrication method of the SOFC having advantages of the pellet process and the tape casting process.